Benchmark: JS Fastest Array Shallow Copy21312312

Tests:

Array.concat
var a = [ "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello" ]; var other = Array.from(a);
Array.slice
var a = [ "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello" ]; var b = a.slice();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.concat
Array.slice

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array.concat	63243080.0 Ops/sec
Array.slice	105881800.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON tests the performance of various methods for shallow copying an array in JavaScript. Specifically, it compares two approaches: using the `Array.from` method and the `Array.slice` method. Each of these methods has its own characteristics, advantages, and potential drawbacks.

### Test Cases

1. **Array.concat**
   - **Benchmark Definition**: 
     ```javascript
     var a = [ /* array of "hello" strings */ ];
     var other = Array.from(a);
     ```
   - **Test Name**: "Array.concat"

2. **Array.slice**
   - **Benchmark Definition**: 
     ```javascript
     var a = [ /* array of "hello" strings */ ];
     var b = a.slice();
     ```
   - **Test Name**: "Array.slice"

### Pros and Cons of Each Approach

- **Array.from**
  - **Pros**: 
    - Clear syntax that indicates copying an iterable (including arrays).
    - Can accept a mapping function as a second argument to transform the elements while copying.
  - **Cons**: 
    - This approach might be less performant than `slice` in certain cases, particularly for large arrays, due to the overhead of the function call and additional features.

- **Array.slice**
  - **Pros**: 
    - Simple and straightforward to use, designed specifically for array copying.
    - Generally faster than `Array.from` for copying a regular array, as shown in the benchmark results.
  - **Cons**: 
    - Less flexible in terms of transformation, as it simply creates a shallow copy without any ability to apply a mapping function directly.

### Benchmark Results

From the latest benchmark results, we see the following performance indicators:

- **Array.slice**
  - **Executions Per Second**: 105,881,800.0
  - **Browser**: Chrome 131
  - **Operating System**: Mac OS X 10.15.7

- **Array.concat**
  - **Executions Per Second**: 63,243,080.0
  - **Browser**: Chrome 131
  - **Operating System**: Mac OS X 10.15.7

The results clearly indicate that `Array.slice` has a much higher execution rate than `Array.from` in this particular test scenario, thus suggesting that it may be a better choice for performance-critical applications where shallow copying of arrays is frequent.

### Other Alternatives for Shallow Copying Arrays

While the benchmark focuses on `Array.from` and `Array.slice`, there are alternative methods to perform shallow copies in JavaScript, including:

- **Spread Operator ([...])**: 
  ```javascript
  var b = [...a];
  ```
  - **Pros**: 
    - Very readable and concise syntax.
    - Can be used in various contexts, such as array concatenation.
  - **Cons**: 
    - It may have slightly different performance characteristics compared to `slice`, but typically this method is also fast.

- **Array.prototype.concat()**: 
  ```javascript
  var b = a.concat();
  ```
  - **Pros**: 
    - Returns a new array with the combined contents, making it useful for copying while also combining arrays.
  - **Cons**: 
    - Can be less intuitive for simple copying, as it is often used for merging.

### Conclusion

In summary, this benchmark evaluates two methods for shallow copying arrays in JavaScript: `Array.from` and `Array.slice`. The results indicate that `Array.slice` provides superior performance in this scenario. While both methods are valid approaches, developers should consider the specific use case and performance implications when choosing how to copy arrays, as well as potential alternatives like the spread operator and `concat` method.

Related benchmarks:

JS Fastest Array Shallow Copy21312312 (version: 1)

Testing the results for the fastest approach of shallow copying an array in JavaScript (concat, slice, for loop, and while loop).

Comparing performance of: Array.concat vs Array.slice

Created: one year ago by: Guest

Jump to the latest result

Array.concat

Array.slice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):